Laminate of cotton paper core with resin phosphorescent material scribed to expose core

ABSTRACT

A phosphorescent material is added to the resin which is utilized to coat the core material in an engraving stock. After the surface material of the engraving stock is scribed into words or signals and the core material is exposed, the latter will phosphoresce in a subnormal amount of light.

United States Patent Williams [4 1 Oct. 23, 1973 LAMINATE 0F COTTONPAPER CORE 2,458,104 1/1949 Schweizer 156/67 WITH RESIN PHOSPHORESCENT2,321,046 6/1943 Rudnick 1l7/33.5 R 1,813,491 7/1931 Gillard 8/1 WMATERIAL SCRIBED To EXPOSE CORE 3,654,044 4/1972 Hirota 161/2 Inventor:Charles J. Williams, Lacrosse, Wis.

Universal Oil Products Company, Des Plaines, 111.

Filed: Oct. 18, 1971 Appl. No.: 190,263

Assignee:

References Cited UNITED STATES PATENTS 9/1906 Aylsworth 8/1 W FOREIGNPATENTS OR APPLlCATlONS 596,852 l/l948 Great Britain 156/62 PrimaryExaminerGeorge F. Lesmes Assistant ExaminerPatricia C. lvesAttorney-James R. Hoatson, Jr. et a1.

[57] ABSTRACT A phosphorescent material is added to the resin which isutilized to coat the core material in an engraving stock. After thesurface material of the engraving stock is scribed into words or signalsand the core material is exposed, the latter will phosphoresce in a subnormal amount of light.

1 Claim, N0 Drawings LAMINATE OF COTTON PAPER CORE WITH RESINPHOSPIIORESCENT MATERIAL SCRIBED TO EXPOSE CORE This invention relatesto articles of manufacture and more particularly to engraving stock.More specifically the invention relates to engraving stock in which thecore material is coated with a resin which contains a phosphorescent dyematerial.

Engraving stock, which is a high pressure laminate, usually comprises acore material which is bonded to a cover material, the cover materialeither covering one side of the core or both sides. The cover materialis usually available in a wide variety of grains or colors and the corematerial is usually in a contrasting color. By scribing the covermaterial by any means, such as an electric saw, sand blasting or machineengraving by pantograph, will result in an article of manufacturecomprising multi-colored signs, etc. The thus formed engraving stock maybe used as an effective means of communication or identification and maybe employed as directional signs, room numbers, name plates, controlpanels, plaques, diagrams, directories, etc., said signs being placed ona wall surface or door in office buildings, hotels and motels,hospitals, schools, etc. However, the signs, room numbers, name plates,etc., usually require a relatively large amount of light in order thatthe signs may be legible or easily visible.

In some instances, however, it is impossible to provide an adequatesource of light whereby the signs, numbers, etc., are readily visible;an example of this would be the cockpit of an airplane in which,especially during flights at night, it is impractical or hazardous tohave the necessary amount of light present in the cockpit which wouldpermit a reading of the instruments or signs. This would also apply tothe bridge of a ship, such as ocean-going passenger liners, freighters,oilers, etc., or the cockpit of a pleasure boat such as'a yacht ormotorboat in which an absence of light in the bridge of the ship orcockpit of the boat is necessary, in order that an adequate watch may behad on the water ahead. Another illustration of an area in which anabsence of light is desirable are places of entertainment in which thestage is illuminated by means of spot lights or foot lights and theremaining area surrounding the stage outside of the immediate area is ineither total darkness or very dim light. In instances where the absenceof light is desirable or required, it is therefore necessary thatdirectional signs, signals, numbers, etc., be illuminated by some othermeans.

It is therefore an object of this invention'to provide an engravingstock which may be utilized for directional signs, numbers, etc. inareas subject to either a subnormal amount of light or an absence ofvisible light.

In one aspect an embodiment of this invention resides in an article ofmanufacture which comprises a laminate consisting of a resin coated corematerial and a surface material bonded to each other, said surfacematerial being scribed to expose the core material, said resin whichcoats said core material containing a phosphorescent material which isinternally activated to luminesce in a subnormal amount of light.

A specific embodiment of this invention is found in an article ofmanufacture which comprises a laminate consisting of an epoxy resincoated cotton paper and a surface material bonded to each other, saidsurface material being scribed to expose said resin coated cotton paper,the epoxy resin which coats said paper containing a non-thermallydegradable phosphorescent material, which is internally activated toluminesce in a subnormal amount of light.

Other objections and embodiments will be formed in the following furtherdetailed description of the invention.

As hereinbefore set forth the present invention is concerned with anarticle of manufacture, and more particularly to engraving stock whichcontains incorporated therein a phosphorescent material. The desiredengraving stock which contains the phosphorescent material may beprepared by admixing a phosphor which is non-thermally degradable innature with a resin such as an epoxy resin, a phenolic-melamine resin, avinyl resin, etc., in an amount in the range of from about 1 percent toabout 3 percent by weight of the resin solids. The aforesaid mixing canbe accomplished by any manner known in the art including physicalmixing, by stirring, or by any other adequate means. Examples ofphosphors which are not thermally degradable under the conditions ofcuring hereinafter set forth in greater detail will include inorganicsulfides which have been activated with other elements. Particularexamples of synthetic phosphors which may be utilized will include thealkaline earth sulfides such as beryllium sulfide, calcium sulfide,strontium sulfide, barium sulfide, etc. which have been activated withvarious elements such as bismuth, copper, manganese, cerium, europium,samarium, etc. In addition it is also contemplated within the scope ofthis invention that other sulfides such as zinc and cadmium sulfidewhich have been activated with bismuth, phosphorous, ammonia, etc. mayalso be used.

The mixture which results from the admixture of the resin with thephosphorescent material is then utilized to coat the core material ofthe engraving stock. One method of effecting this coating orimpregnation is to charge the-core material which, as hereinbefore setforth, may comprise a cotton paper or any other type of paper to a tankcontaining the resin-phosphorescent material mixture. Following thispassage through the tank, the coated core material is passed throughsqueeze rolls, the space between said rolls being of various thicknesseswhich will control the amount of resin mixture which will remain on andcoat the paper core material. After passage through the squeeze rollswhereby the excess resin mixture is removed, the coated core material isthereafter passed into a curing oven wherein the resin is cured. In oneembodiment the curing oven will comprise two heating zones, the initialheating zone being maintained at a temperature from about 220F to 240F.After passage through this heating zone, the resin coated core materialis passed through a second heating zone at a slightly elevatedtemperature, the temperature of the second heating zone being from 240to 260F. After passage through the curing oven, the core material whichis coated with the cured resin, the latter containing the phosphorescentmaterial, is recovered. Thereafter, the core material is cut into thedesired size and shape and a sufficient number of the core materialsheets are stacked to give the desired thickness of the core. If sodesired, in another embodiment of the invention, it is possible toutilize a core material which has not been coated with thephosphorescent containing resin for the desired number of sheets in theinner core, thus only utilizing the resin coated core material as theoutermost ply in the finished core laminate. While it is possible toutilize various colors for the core material, the preferred color forthe core material will be white, in order that it may afford thegreatest contrast when utilizing cover material of various other colors.

After completion of the preparation of the core material with thepredetermined number of ply to effect the desired thickness of saidcore, a surface material which may also be of paper, plastic or anyother suitable material is bonded to the core material. In the preferredembodiment of the invention the surface material will be wood grained,leather grained or of a contrasting color such as yellow, red, blue,green, gray, black, brown, etc. when compared to the color of the corematerial in order that, after being scribed, the core material willpermit the various signs, numbers, names, etc. to be easily legible inordinary light. The laminate thus prepared which comprises the twosurface coatings and the core material is placed between stainless steelplates which have been treated with a release material such as a stearicacid solution to facilitate removal of the stock after lamination andsubjected to a sufficient amount of pressure for a predetermined periodof time whereby an effective bond is formed by the surface material andthe core material. As an example of this step of the process, thelaminate may be subjected to a hydraulic pressure of from about 1,000 toabout 2,000 pounds per square inch at a temperature in a range of fromabout 270 to about 280F. for a period of from about 0.5 to about 1 hour.One percent strength is utilized to release the thus formed lamanatefrom the stainless steel plates. As hereinbefore set forth, it is to benoted that a required characteristic of the phosphorescent materialwhich is admixed with the resin is that it must be nonthermallydegradable under the coating conditions and in the pressure conditionswhich are required to effect the preparation of the desired laminate,that is, said material must be able to withstand a temperature ofapproximately 300F. and still retain its ability to luminesce.

The thus formed laminate is then scribed by various means hereinbeforeset forth in greater detail such as by an electric saw, sand-blasting,pantograph engraving, etc., whereby the desired sign, number, name,diagram, design, emblem, trademark, etc. is transcribed through thesurface material and the core material of contrasting color is exposed.

When utilizing the engraving stock in an area in which there is anabsence of said light, the phosphorescent containing resin which coatsthe core material will luminesce and thus illuminate the desired sign,etc. This luminescence will take place due to the activation of thephosphor, usually by natural light which has impinged on the exposedsurface of the resin coated core material of the engraving stock duringthe daylight hours. However, if the particular engraving stock ispositioned so that it is impossible to activate the same by exposure tonatural light the phosphor may be radiated with an exciting light toactivate the luminescence of the phosphor. This exciting or activatinglight may be provided for by a light source such as an ultra-violetlight having a wave length less than about 4,000A. and usually in alength from about 25000A. to about 4,000A. The ultra-violet light mayemanate from a low pressure mercury vapor lamp where the predominateemission is a wave length of 2,537A., or from a high pressure mercuryvapor lamp, a tungsten lamp, a carbon lamp, etc. The thus activatedphosphorescent material will reflect a useful visible light of constantintensity and will therefore render the desired sign, number, name,design, etc. visible and readable.

As an illustrative example of an article of manufacture of the presentinvention a core material comprising 'a cotton paper is coated withresin mix which has been prepared by physically admixing an epoxy resin,such as that resulting from the reaction between chlorohydrin andbisphenol-A, and 2 percent by weight of a fluorescent materialcomprising strontium sulfide which is activated with bismuth. Thecoating step in the preparation of the article of manufacture of thepresent invention is effected by feeding the cotton paper through a tankof the resin-phosphor mix and thereafter pressing the coated paperthrough squeeze rolls whereby the excess mix is removed from the surfaceof the paper. Following this, the coated paper is passed through acuring oven which has a temperature at the inlet portion of the oven of230F and a temperature of 250F adjacent to the outlet portion of theoven. After removal from the curing oven, the core material which iscoated with the aforementioned resin-phosphor mix is placed between twolayers of a surface material which also comprises a cotton paper andwhich is of a contrasting color such as black as compared to the colorof the core material which is white. The three-ply of the laminate arepressed between stainless steel plates which have been treated with arelease material comprising a 1 percent stearic acid solution andpressed for 40 minutes at a temperature of 50 pounds of steam and atemperature of 280F., the hydrogen pressure which is maintained duringthe 40-minute period being 1,400 per square inch. At the end of the 40-minute press period, the stainless steel plates are removed and thestock is recovered. The resulting laminate is scribed by means ofpantographic engraving whereby the surface material is removed to exposeresin coated core material, the particular design being scribed on thecore material being a directional arrow. The engraving stock is then cutto the desired size and placed on a wall by any means known in the artsuch as by the use of wood, sheet metal or machine screws, double sidedpressure sensitive tape, or by the use of an epoxy adhesive that willadhere to plaster, paint, wood, glass, metal laminate, or whatever thesurface of the wall may comprise. The engraving stock will luminesce inthe absence of light due to the phosphorescent material contained in theresin which coats the core material and thus will afford a directionalsignal in the absence of light. Alternatively if there is no naturallight source available to excite the phosphor, said phosphor willluminesce when exposed to the activating rays emanating from anultra-violet light source.

It is to be understood that the above example is given merely for thepurpose of illustrating the present invention and that the novelarticles of manufacture are not necessarily limited thereto.

I claim as my invention:

1. An article of manufacture comprising a laminate consisting of a resincoated cotton paper core material and a surface material bonded to saidcore material, said resin selected from the group consisting of epoxyresin and phenolic-melamine resin, said resin containing aphosphorescent material selected from the group consisting of strontiumsulfide activated with bismuth, barium sulfide activated with bismuthand zinc sulfide activated with bismuth, said surface material beingscribed to expose said core material, said phosphorescent material beingadapted to be internally activated to luminesce in a sub-normal amountof light.

